the arctic tundra case study

  • Created by: beaw18
  • Created on: 21-05-19 09:14
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  • arctic tundra
    • locate
      • area of 8 million km
      • found in northern canada, alaska, siberia
      • conditions get more severe with latitude
      • for 8-9 months of year tundra has temps below freezing
      • ground is permanently frozen, top meter thaws in summer
      • soil underlain  by permafrost
    • water cycle
      • low annual precipitation of 50-350 mm. most of this is snow
      • small moisture store in atmosphere - low temps and absolute humidity
      • limited transpiration - sparse vegetation and small growing season
      • evaporation rates low due to lack of sun energy, energy generally used to melt snow
      • groundwater and soil water stores small as permafrost is a barrier to infiltration, percolation and groundwater flow
      • increased river flow in spring as snow and ice thaw
      • extensive ponds, wetlands and lakes during summer as drainage is poor
    • physical factors, seasonal changes and stores and flows of water
      • average temps well below freezing, most water is stored in ice, snow and permafrost
      • summer - active (top meter) thaws and liquid water pools on surface
      • drainage is poor as water cannot infiltrate frozen soils
      • sub zero temps prevent evapotranspiration
      • permeability low as rock basin is crystalline
    • carbon cycle
      • permafrost a carbon sink - 1600 gt of carbon
      • accumulation of carbon is slow due to low temps which slow decomposition rates
      • amount of carbon in soils is 5x than above ground biomass
      • plants grow rapidly in short summer - long days of sunlight allow max growing
      • npp is less than 200 grams per square meter a year
      • biomass small - between 4 and 29 tonnes a year
      • tundra plants input carbon rich litter into soil. microorganism activity increase releasing co2 through respiration
      • pockets of unfrozen soil act as co2 and methane sources
        • debatable if this will happen, scientists investigating
    • physical factors, seasonal changes and stores and flows of carbon
      • carbon mostly stored in decomposing plants trapped in permafrost for last 50,000 years
      • low temps and water logging slow decomposition and respiration rates - flow to atmosphere slow
    • oil and gas production impacts
      • the north slope of alaska - oil and gas discovered at prudhoe bay in 1968
        • despite extremities, pipelines, roads, completed in 70/80s
      • 90s - bay accounted for 3/4 of US's domestic oil production
        • today only 6% due to growth is US shale gas, and production costs
      • damages permafrost from construction and operations
        • snow darkened by dirt, absorbs heat
        • vegetation which insulated vegetation gone
        • heat from settlements diffused directly
      • melting permafrost releases co2 and methane - green house gases
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